As a matter of precaution, Drew had taken his revolver from his belt and held it ready in his hand. He had really no expectation of meeting anything hostile in human shape and he did not believe that any animal that would be at all formidable ranged the island. "If it's a ghost, I don't suppose this revolver would do any good," he joked, more to relieve Ruth's uneasiness than any that he felt himself. "At the very least I'd have to have a silver bullet or one that had been dipped in the river Jordan." The opening before which they stood was irregular in shape and seemed to have been made by one of the convulsions of nature that apparently were so common to the island. It was, roughly speaking, about four feet wide and nine high, and from the glimpse they got into its depths seemed to widen out in the interior. There was nothing about it to speak of human occupancy and the ground leading to it bore no marks of footprints. Nor were there any bones scattered about that might indicate that it was the lair of wild beasts. Drew cupped his hands to his mouth and sent forth a ringing call. "Hello, in there!" he shouted. There was no answer, but the reverberations of his own voice that came back to him seemed to show that the cave extended inward to a considerable depth. "Hello!" he shouted again. "If there's any one in there, come out! We're friends and won't hurt you." Again there was no answer. "Doesn't seem to be sociably inclined," muttered Allen grimly. "I guess there's nobody there," said Ruth. "Let's go back to the others, Allen. We've spent too much time already on this foolish notion of mine." "It wasn't foolish at all," protested Drew. "As a matter of fact it may prove to be of the greatest importance. We ought to sift the matter to the bottom. If there's anybody on this island we don't know about, it ought to be our first business to find out. I think I'll take a peep into this mysterious cave." He made a step forward, but Ruth's hand tightened on his arm and he stopped. "Do you think you'd better risk it, Allen?" she asked. "How do you know what may be in there. Suppose--suppose----" "Suppose what?" he asked with a whimsical smile. "Suppose anything should happen to you?" she half whispered. "Nothing will happen to me," he rejoined. "Not that it matters much anyway," he added bitterly, as the thought swept over him of the black cloud of suspicion that hung above him. "Just give me a minute, Ruth," he pleaded, hating himself for his reckless words as he saw the pained look in her eyes. "I won't go in for more than twenty or thirty feet, just to see if there's anything about this place that we really ought to know. You stay here and I'll be back before you fairly know I've gone." She reluctantly loosened her grasp of his arm and he plunged forward into the darkness.